At the present time, there are known microwave ovens which comprise grill elements, i.e. means for irradiation of foodstuffs which are to be cooked in the oven with IR radiation, in order to create a grilled texture of said foodstuffs.
The conventional method is to arrange grill elements outside the oven cavity, in a so-called grill bulge, in order to avoid creating serious disturbances of the microwave pattern in the oven cavity. However, this results in new problems since a route must be created for the IR rays into the oven cavity, which route leads to the creation of an opening in the cavity wall through which microwaves pass into the grill bulge, from where the microwaves can leak out into the surrounding room.
In order to avoid such leakage a solution has been created, which is presented in EP 0 420 319. The invention defined in this patent aims to prevent the microwave field present in the grill bulge from leaking out into the surrounding room. In order to achieve this, measures are taken in two steps: the first step is the arrangement of a perforated metal sheet in the opening of the cavity wall so that this sheet physically shields the grill bulge from the cavity. Even though this shield shields off some of the microwaves, the resulting field in the grill bulge is still relatively strong, which causes problems with radiation leakage to the surrounding room. The second step is that in order to prevent this leakage to the surrounding room, one has attempted to insulate the grill bulge from the surroundings in such a way that the relatively substantial amount of microwaves which, despite the sheet, make their way into the grill bulge do not penetrate into the surrounding room. This insulation has substantially been created by the sheet being in electric contact with a metallic reflector arranged in the grill bulge, which reflector is used to reflect IR radiation from the grill elements in the oven cavity. The reflector and the sheet are electrically insulated from the walls of the oven cavity so that they form a cage, which acts as a microwave seal in relation to the surrounding room.
A special difficulty in this context are the electric connections of the grill elements, which connections function as antennae for the microwaves. The microwaves picked up by them can then escape from the grill bulge by the intermediary of those wires from the connections which lead out from the bulge. In order to prevent this, a specially configured shielding arrangement for the connections and their conductors are shown in the patent, which arrangement has the task of reflecting the microwaves back into the grill bulge.